Key cap



K. FLADER June 14, 1938.

KEY CAP Filed Nov. 14, 1955 7mm mam/940 H400? Patented June 14, 1938UNITED STATES KEY CAP Konrad Flader, Hochheim, near Erfnrt, Germany,assignor to Olympia Biiromascliinenwerke Aktiengesellscliaft, Erfnrt,Germany Application November 14, 1935, Serial No. 49,703 In GermanyOctober 31, 1933 7 Claims.

My invention relates to improvements in key caps for typewriters,calculating and other key operated machines, the key caps of which areusually provided at their upper face with one or more identificationmarks, such as letters. fig'-' ures, symbols, stops, collectivelyhereinafter called "characters, and at their bottom with a shank or stemconnecting the cap with the key lever.

10 The various objects aimed at by this invention and the advantagesobtained will be more fully understood by first reviewing some of theprincipal structural characteristics of and the drawbacks inherent tokey caps of known de sign.

caps by carving or engraving them in the form of shallow notches orrecesses into the upper face of the key cap, filling the recesses withan adhesive, colored paste, paint etc., and allowing the filled inmaterial to dry and become hard,

or else the characters were stamped out of thin sheets of celluloid soas to closely match the recesses in the caps and were inserted into thelatter, and afilxed similarly to the inlaid work of fine furniture andpieces of art.

In both cases the has-relief patterns or recesses were rather shallow asto their depth, particularly since such tiny patterns having clean cutedges can only be obtained by stamping thin sheets of celluloid.

As a matter of course both kinds of the characters described, viz,thoseof dried paint and those of celluloid, are subject to rapid wear,viz,

to be scratched by the typistsfinger-nail's, dissolved and discolored byhuman perspiration, to be loosened, broken and torn out of their 40edges and corners of those inlaid characters of celluloid, which werenot quite flush with-the other surface of the cap,

Recently another type of cap has been widely used, the characters ofwhich are printed on small pieces of card board, the latter beingcovered by thin plates of glass and secured to the keyboards providedtherewith, because of pres senting so many surfaces of glass .and shiny55 light-reflecting metal rings, have a somewhat Heretofore characterswere applied to the key glittering and glaring appearance irritating orI tiring to the typist. I

The principal object of this invention is to overcome the aforesaiddrawbacks by providing improved characters for key caps of simple andwear resisting design, which can be made at low cost by mass-production.

Another salient feature of the invention-is the provision of simplemeans for producing and permanently providing the cap with characters 10which are u not detachable; or readily damaged by scratchingordiscolored by perspiration.

In connection therewith the inventionaims at providing also improvedmeans for securingthe stem to the cap in a simple and inexpensive 15manner, thereby further reducing the production costs of key operatedmachines.

Other objects of this invention will become incidentally apparenthereinafter to experts in field. Y 20 The nature and scope of thisinvention are briefly outlinedin the appended claimsand will be morefully understood from the following.

specification, taken together-with the accompanying drawing, in whichFig. 1 is a fragmentary section taken verti- 'c'ally through a mould,for making caps of im-'-' proved design according to this invention; the

' cap proper and the bottom portion of the mould being shown in sectionalong line IIII in Fig- 30 ure2;

Fig. 2 is a plan showing the cap as seen from below and the stemincorporated therein; Fig. 3 is a perspective view ofthe cap'as .itcomes outof themould';

Fig; 41s a perspective 'view of-the bottom part of the'mould; places,and are also rather insanitary because 1 dirt and dust would accumulatein the receding Fig.5 is atop view, on. .cap providedwith somewhatcomplicated and extensive characters;

Fig. 6 is a section of the cap taken oh line V-VinFia-S} w a Fig. ",7 isa diagrammatic" lay-out, showing by way of an'example a means-forfilling the chan- ,nels and recesses (characters) of the cap with v I aplastic composition, which will subsequently 45 ri'gidify andthenbe orrelatively great hardness; 5 f

Fig. 8 shows perspectively and in an enlarged scale one of the blocks ortablets for recharging the mould shown in F'ig. 1; said'tablets areobtained by briquetting' definite quantities of a composition of matterin bulk, from which the improved. caps arepreferably made. 1 In Figures1-7 ithe drawing the key 'cap is shown in a scale larger than its usualsize;

fiedmasslenclosedinslrid channels {actingasanchorsandsecurelyretainingtbecharacters of the cap in-their position:

(4) With a stem i projecting from the lower face of the cap 2 for latterto the key lever (not shown) of a typewriting or other 'key operatedmachine.

Thesaidstemiispreierabiysecuredtothe cap 2 by incorporating or wits.upper end into the material, of which the cap is made, and while saidmaterial is in plastic condition.

'- Key-caps re-designed according to this invention are made toadvantage as articles of mass production from one of those resinouscompositions of ,matter, collectively called by chemists phenopiasts andaminoplasts" and known to the public under various trade-names. 'Thecharacters appearing at the upper face of the cap like inlaid work arepreferably made of acetyl-cellulose, which is heated so as to become aplastic mass and is injected under considerable pressure through thechannels 4 into the recesses l of the cap, completely filling the latterup tothe remctest corner, and being flush with the upper surface of thecap.

Using acetyl-cellulose for'iilling the 3 is advantageous because onbecoming rigid it presents a hard and wear-resisting mass having asmooth, vitreous-like surface and substantially the same coeiiicient ofthermic expansion as those resinous materials from which the cap properis preferably made.

However I wish it to be understood, that my claims are not limited tousing acetyl-cellulose for the purpose set forth, dnce other materialsor compositions of matter having the same properties may be found, whichare equally useful and applicable. I

I have found it advantageous to make key caps re-designed according tothis invention by a process described hereinafter and by using apparatusshown by way of examples in Figs. 1 and 'i.

Fig.1 shows a mould,theintericr of whichis an exact replica of the capto be made and which consists of a lower section or base ll, an upper;secticnor lid ll; means diagrammatically indicat'ed-at II and Iiareprovided for heating the mould and means (not shown) forreciprocating the lid II and keeping it pressed with hi h pressureagainst in the mould.

The bottom piece it of the mould which may be conveniently made le anddesigned as an ejector, is formed with the respective character orcharacters of the 'cap in hautrelief, namely in the I form of relativelyhigh ridges ll projecting from the upper face of bot-- tom piece It. Thelid II of the mould isformed arcades at its lower face with a pluralityof conical ttuds If so designed as to terminate closely above the saidridges I, when the mould is closed and underpressure; in the center oflid a recess is formed closely fitting the stem lot the cap which isinserted thereinto before the mould is closed. The depth of thesaid-recess on the lid 2| is so chosen, that on closing the mould thestem' I is forced into the briquet B and is thus inccrporated into thematerial of the cap.

0n opening the mould the cap 2 is allowed to cool and become rigid andwill then be ready for the finishing operations, the latter comprisingremoving the burr formed at the circumferential edges of the cap and inthe channels 4, viz., between the opposed faces 0 the-ridges I4 and theconical, studs 2! (Fig.1), and filling the channels 4 and recesses 3 ofthe cap with a plastic composition, which will become rigid when coldand present a hard vitreous mass of the nature described above.

The said plastic composition is preferably injected into the cap 2 bymeans of an apparatus,

- shown by way of an example in Fig. 7 and comprising:

- A base plate formed with a recess, the latter .fitting the characterbearing upper face of the cap, a cylinder 3| containing the plasticcomposition concerned and being heated preferably by electricity asindicated at 82, a piston 33 operated by a lever 34 for ejecting theplastic composition under pressure from the cylinder fl, and a pluralityof pipes 35 having nozzles 38 formed at their ends for injecting theplastic composition into the channels 4 and recesses l of the cap. a

Various changes and modifications may be conveniently made in thestructural details of key-caps of the improved-design describedhereinbefore, in the materials and compositions used,

and in the method and means for making those caps shown by way ofexamples in the drawing, without substantially departing from'the spiritand the salient ideas of this invention.

Inscriptions of key caps, which consist of several letters, symbols etc.spaced from each other, for instance tab-clear (Fig. 5), or areotherwise subdivided into a number of parts may be underlined toadvantage as indicated at I in Fig. 5, so as to bodily associate. andinterconnect by a common structural element, namely an additional orauxiliary recess, the various letters concerned, thus keeping themjointly secured within the cap, and also reducing the number of anchorsand channels 4 which would be otherwise required for filling theindividual recesses pertaining to each of the letters etc. of theinscription. The stem I oithe cap may be conveniently provided with acrosshead twisted at its ends, as indicatedat 5', so as to spread outand enlarge the faces of contact with the material of the cap. It willbe noted that-the ends I are curved away from the line of the straightportion of the cross head between them.

Although resinous compositions, which can be molded in virgin conditionunder heat and pressure and will be converted when cold into a hard massof great density and tenacity, not softened by heat subsequentlyapplied, have been found to be suitable materials for making key capsdesigned according to this invention, particularly because the caps willnot be deformed or discolored by the heat subsequently applied byiniecting a hotplastic substance into the channels and recesses I, l ofthe caps (Fig. 7), I do not an element for attaching the cap to a keylever having a shank extending from said cap, said channels beinglocated laterally of and spaced from said shank.

2. In a key-capfor key operated machines, the combination with recessesin the form of basrelief characters on top of the cap, of channelscommunicating with said recesses and terminating at the bottom face ofthe cap, a hardened mass enclosed in said channels and recesses, saidtransverse channels being of conical shape and converging towards saidrecesses, and an-element for attaching the cap to a key lever having ashank extending from said cap, said channels being located laterally ofand spaced from said shank.

3. In a key-cap for key operated machines, the combination with recessesin the form of basreliei' characters on top of the cap, of channelscommunicating with said recesses and terminating at the bottom face ofthe cap, a hardened mass enclosed in said channels and recesses, saidcap consisting of a resinous composition of matter, adapted to bemoulded under heat and pressure, solidifying when cold, and notregaining plasticity on being reheated, and an element for attaching thecap to a key lever having a shank extending from said cap, said channelsbeing located laterally of and spaced from said shank.

4. In a key-cap for key operated machines, the combination with recessesin the form of basrelief characters on top of the cap. of channelscommunicating with said recesses and terminating at the bottom face ofthe cap, a hardened mass enclosed in said channels and recesses. saidhardened mass consisting of an acetyl-cellulose composition, adapted tobe moulded under heat and pressure and vitrifying when cold, and anelement for attaching the cap to a key lever having a shank extendingfrom said cap, said chan'-.

nels being located laterally of and spaced from said shank.

5. In a key-cap for key operated machines, the combination with recessesin the form oi bas-re-' lief characters on top of the cap, of channelscommunicating with said recesses and terminating at the bottom of thecap, a hardened mass enclosed in said channels and recesses, saidchannels being interconnected by said recesses, and an element forattaching the cap to a key lever having a shank extending from said cap,said channels being located laterally of and spaced from said shank.

6. In a key-cap for key operated machines, the combination with recessesin the form of bas-re- .lief characters on top of the cap, of channelscommunicating with said recesses and terminating at the bottom of thecap, a hardened mass enclosed in said channels and recesses, and a stemfor attaching the cap to a key lever incorporated in said cap, said stemincluding a bar adapted to be embedded in the cap and extendingsubstantially parallel to the face of the cap and a shank for attachmentprojecting from said cap and substantially at right angles to said bar,said channels being located laterally of and spaced from said shank.

'1. In a key-cap for key operated machines, the combination withrecesses in the form of basrelief characters on top of the cap, ofchannels communicating with said recesses and terminating at thebottomof the cap, a hardened mass enclosed in said channels and recesses, anda stem for attaching the cap to a key lever incorporated in said cap,said stem including a bar adapted to be embedded in the cap andextending substantially parallel to the face of the cap and a shank forattachment projecting from said cap and substantially at right angles tosaid bar, said bar having the opposite ends thereof curved in oppositedirections, said channels being located laterally of and spaced fromsaid shank.

KONRAD FLADER.

